Arbitrary-Ratio Image/Video Resizing Using Fast DCT of Composite Length for DCT-Based Transcoder
Dipika P.Chanmanwar1, Priyanka S. Ghode2

1Dipika Chanmanwar, Lecturer in Government Polytechnic, Nagpur (Maharastra), India
2Priyanka Ghode, Lecturer in Government Polytechnic, Nagpur (Maharastra), India
Manuscript received on August 05, 2013. | Revised Manuscript Received on August 26, 2013. | Manuscript published on August 20, 2013. | PP: 14-17 | Volume-1, Issue-9, August 2013. | Retrieval Number: I0280081913/2013©BEIESP
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Abstract: The most popular image and video compression methods such as JPEG, MPEG 1/2/4, H.261/3/4 use transform domain techniques and in particular the Discrete Cosine Transform (DCT). One application for such images or video sequences is resizing. Resizing is extensively used to meet the requirements of a specific system, to satisfy user’s interests, or to correct spatial distortions. However, a major difficulty encountered when resizing such media is the high computational complexity and the loss of quality caused by the decompression and compression. The purpose of this paper is to implement an arbitrary ratio image resizing scheme in the DCT domain for transcoding of the compressed images. There are several advantages in working in the DCT domain, of these advantages the one that stands out the most is the fact that images are stored in the DCT domain and therefore no initial computation is needed in order to work on the image. The downsizing process in the discrete cosine transform (DCT) domain can be implemented by truncating high-frequency coefficients, whereas the upsizing process is implemented in the DCT domain by padding zero coefficients to the high-frequency part. The implemented method combines a fast inverse and forward DCT of composite length for arbitraryratio upsizing or downsizing. The implemented method shows a good peak signal-to-noise ratio and less computational complexity compared with the spatial-domain and previous DCT-domain image resizing methods. Further it will compare several methods offered by different authors for image resizing. The implemented method of arbitrary ratio image resizing improve peak signal-to-noise ratio and reduces computational complexity when compared with other existing methods. This implemented approach of image resizing is extended for video resizing. The PSNR values of the resized video are calculated by using an existing tool. The obtained PSNR values are better when compared with other existing tools.
Keywords: Arbitrary-ratio image resizing, composite length DCT, transcoder.